In a conventional chewing gum manufacturing process, a double arm Sigma blade mixer is used to mix chewing gum ingredients. Gum base, bulking agents such as sugar or sorbitol for sugarless gum, liquids such as syrup or liquid sorbitol, softeners such as glycerin and lecithin, and flavors are mixed about 5-20 minutes to manufacture the gum.
The warm, dough-like gum mass is removed from the mixer and added to a kneader from which it is forced or sheeted into a ribbon or rope to be formed into chunks, pellets, tabs, or sticks. After cooling, pellet gum is coated, but the other forms are wrapped in high speed wrapping machines. During this process some gum is not suitable for wrapping or some wrapped gum is not suitable for sale. Gum product may become damaged during kneading, cooling, transferring or wrapping, or wrapped product may not be properly packaged. All of this gum is called rework or recycle gum.
Generally, rework gum from the mixer, rework gum from the kneader, or rework gum formed during sheeting can be returned to the kneader and reworked because it is still fresh and warm. However, gum that has cooled or aged several days for wrapping is not suitable for the kneader, but needs to be added to the Sigma blade gum mixer. Gum which has passed its expiration date may also be unwrapped and mixed with fresh gum ingredients in the Sigma blade mixer. Generally about 5 to about 50% of the formula manufactured in the Sigma blade mixer may be from rework gum. Preferably rework gum may be about 10 to 25%, and most preferably about 15 to 20% of the total batch formula may be rework gum, with the remainder being fresh ingredients.
In gum manufacturing, aged rework gum added to a gum mixer not only allows for elimination of waste, but also improves the texture of the gum for handling and helps stabilize the texture during storage. The aged rework gum, whether it be one day aged or longer, has the effect of improving the texture by making it slightly tougher for handling in sheeting, cooling and wrapping.
Conventionally, chewing gum base and chewing gum products have been manufactured using separate mixers, different mixing technologies and, often, at different factories. One reason for this is that the optimum conditions for manufacturing gum base, and for manufacturing chewing gum from gum base and other ingredients such as sweeteners and flavors, are so different that it has been impractical to integrate both tasks. Chewing gum base manufacture, on the one hand, involves the dispersive (often high shear) mixing of difficult-to-blend ingredients such as elastomer, filler, elastomer plasticizer, base softeners/emulsifiers and, sometimes wax, and typically requires long mixing times. Chewing gum product manufacture, on the other hand, involves combining the gum base with more delicate ingredients such as product softeners, bulk sweeteners, high intensity sweeteners and flavoring agents using distributive (generally lower shear) mixing, for shorter periods.
In order to improve the efficiency of gum base and gum product manufacture, there has been a trend toward the continuous manufacture of chewing gum bases and products. U.S. Pat. No. 3,995,064, issued to Ehrgott et al., discloses the continuous manufacture of gum base using a sequence of mixers or a single variable mixer. U.S. Pat. No. 4,459,311, issued to DeTora et al., also discloses the continuous manufacture of gum base using a sequence of mixers. Other continuous gum base manufacturing processes are disclosed in European Patent Publication No. 0,273,809 (General Foods France) and in French Patent Publication No. 2,635,441 (General Foods France).
U.S. Pat. No. 5,045,325, issued to Lesko et al., and U.S. Pat. No. 4,555,407, issued to Kramer et al., disclose processes for the continuous production of chewing gum products. In each case, however, the gum base is initially prepared separately and is simply added into the process. U.S. Pat. No. 4,968,511, issued to D'Amelia et al., discloses a chewing gum product containing certain vinyl polymers which can be produced in a direct one-step process not requiring the separate manufacture of gum base. However, the disclosure focuses on batch mixing processes not having the efficiency and product consistency achieved with continuous mixing. Also, the single-step processes are limited to chewing gums containing unconventional bases which lack elastomers and other critical ingredients. Furthermore, no provision is made in these processes for using rework or recycle gum.
In order to simplify and minimize the cost of chewing gum manufacture, there is a need or desire in the chewing gum industry for a continuous system for making chewing gum that can use the rework gum that is conventionally added to the Sigma blade batch mixer. Even more beneficial would be an integrated continuous manufacturing process having the ability to combine chewing gum base ingredients, other chewing gum ingredients and rework gum in a single mixer, which can be used to manufacture a wide variety of chewing gums.